1,1'-{(Hexane-1,6-di-yl)bis-[(aza-niumylyl-idene)methanylyl-idene]}bis-(naphthalen-2-olate).

The whole molecule of the title Schiff base compound, C28H28N2O2, is generated by inversion symmetry. It is formed from two units of ortho-hy­droxy­naphthaldehyde bridged with 1,6-di­amino­hexane. The N atoms are protonated and, thus, the structure is a bis-zwitterionic compound in the solid state. The zwitterion shows strong intra­molecular N—H⋯O hydrogen bonds between the iminium N and the naphthaleno­late O atoms.